The automatic identification system (AIS) is a short range coastal tracking system used on ships and by vessel traffic services (VTS) for identifying and locating vessels. AIS accomplishes this by electronically exchanging data with other nearby ships and VTS stations. AIS information supplements, but does not replace, marine radar, which continues to be the primary method of collision avoidance for water transport.
To exchange information, a maritime mobile service identity (MMSI), which is a series of nine digits which are sent in digital form over a radio frequency channel in order to uniquely identify ships, can be transmitted by AIS to ship earth stations, coast stations, coast earth stations, and other ships. The nine-digit MMSI format allows for use by telephone and telex subscribers connected to the general telecommunications network to call ships automatically. The international maritime organization's (IMO) international convention for the safety of life at sea (SOLAS) requires AIS to be fitted aboard international voyaging ships with gross tonnage (GT) of 300 or more tons, and all passenger ships regardless of size. It is estimated that more than 40,000 ships currently carry AIS equipment. In sum, AIS can be a very powerful tool for managing vessel information.
Notwithstanding the above, one of the shortcoming of AIS is that a participating vessel must voluntarily report information about itself. There is no way to verify that a vessel's position, course and speed are that same as what it is reporting. Satellite imagery is one method of determining such accurate information about a ship, but there it is very difficult to determine which ships are being processed. Accordingly, it is often desired to supplement satellite imagery information with AIS, and vice versa, in order to obtain a clearer picture of vessels in a given area of interest.
In general, fusion of AIS position information with vessels identified in imagery is currently a manual process where AIS tracks are manually overlaid over a manually exploited image. The overlay displayed does not combine or fuse information from the two sources. There is no mathematical fusion that occurs. The process is simply a data dump of information. An analyst examining the final product will have to use subjective judgment to determine which AIS reports most likely correspond to vessels identified in the image. Current efforts in the area of automatic fusion of imagery with other intelligence sources use only latitude and longitude to determine which position reports match to vessels in the scene. Initial attempts ignore feature information, such as length, width, heading, and ship type, which can be obtained from an automated ship detection software system.
In view of the above, one object of the present invention is to provide an automated image identification system and method that effectively fuses satellite imagery with vessel reporting databases such as AIS. Another object of the present invention is to provide a system and method for fusing overhead imagery with automatic vessel reporting systems that reduces the chance of attributing a vessel identified in an image to an AIS position report with false information. Yet another object of the present invention is to provide a system and method for fusing overhead imagery with automatic vessel reporting systems that quickly and effectively allows analysts to identify vessels that are reporting false or spoofed information. Still another object of the present invention is to provide an automated image identification system and method provide intelligence agencies and the fleet with a more detailed operational picture to be used in combination with existing vessel tracking technologies, by identifying vessels that have gone dark (vessels that have stopped emitting position reports). An object of the present invention is to provide an automated image identification system and method that fuses satellite imagery with AIS information in near real-time. Another object of the present invention is to provide an automated image identification system and method that fuses satellite imagery with AIS information at a high throughput to allow for processing of vessel information in high traffic areas. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.